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Versions: 00 01                                                         
cellar                                                         S. Lhomme
Internet-Draft
Intended status: Standards Track                               M. Bunkus
Expires: 2 November 2022
                                                                 D. Rice
                                                              1 May 2022


         Matroska Media Container Chapter Codecs Specifications
                  draft-ietf-cellar-chapter-codecs-01

Abstract

   This document defines common Matroska Chapter Codecs, the basic
   Matroska Script and the DVD inspired DVD menu.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 2 November 2022.

Copyright Notice

   Copyright (c) 2022 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components
   extracted from this document must include Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.





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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Status of this document . . . . . . . . . . . . . . . . . . .   2
   3.  Security Considerations . . . . . . . . . . . . . . . . . . .   2
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   2
   5.  Notation and Conventions  . . . . . . . . . . . . . . . . . .   2
   6.  Matroska Chapter Codecs . . . . . . . . . . . . . . . . . . .   3
     6.1.  Segment Linking . . . . . . . . . . . . . . . . . . . . .   3
   7.  Matroska Chapter Codecs and Nested Chapters . . . . . . . . .   3
     7.1.  Matroska Script (0) . . . . . . . . . . . . . . . . . . .   4
     7.2.  DVD menu (1)  . . . . . . . . . . . . . . . . . . . . . .   5
   8.  Normative References  . . . . . . . . . . . . . . . . . . . .   7
   9.  Informative References  . . . . . . . . . . . . . . . . . . .   7
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   7

1.  Introduction

   _TODO_

2.  Status of this document

   This document is a work-in-progress specification defining the
   Matroska file format as part of the IETF Cellar working group
   (https://datatracker.ietf.org/wg/cellar/charter/).  It uses basic
   elements and concepts already defined in the Matroska specifications
   defined by this workgroup.

3.  Security Considerations

   Tag values can be either strings or binary blobs.  This document
   inherits security considerations from the EBML and Matroska
   documents.

4.  IANA Considerations

   To be determined.

5.  Notation and Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.






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6.  Matroska Chapter Codecs

   Chapter codecs are a way to add more complex playback features than
   the usual linear playback.

   Some ChapProcess elements hold commands to execute when entering/
   leaving a chapter.

   When chapter codecs are used the EditionFlagOrdered of the edition
   they belong to MUST be set.

6.1.  Segment Linking

   Chapter Codecs can reference another Segment and jump to that
   Segment.

   The Chapter Codecs MAY store the Segment information in their own
   format, possibly not using the SegmentUID format.  The
   ChapterTranslate element and its child elements SHOULD be used to
   link the internal chapter codec representation, the chapter codec
   number and the actual Segment it represents.

   For example if a chapter codec of type "1" in SegmentA needs to link
   to SegmentB, it can store that information as "SegB" in its internal
   data.

   The translation ChapterTranslate in SegmentB would use the following
   elements: * ChapterTranslate\ChapterTranslateCodec = 1 *
   ChapterTranslate\ChapterTranslateID = "SegB"

   The Matroska Player MUST use the SegmentFamily to find all Segments
   that need translation between the chapter codec values and the actual
   segment it targets.

7.  Matroska Chapter Codecs and Nested Chapters

   When Nested Chapters contain chapters codecs -- via the ChapProcess
   Element -- the enter/leave commands -- ChapProcessTime Element --
   MUST be executed in a specific order, if the Matroska Player supports
   the chapter codecs included in the chapters.











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   When starting playback, the Matroska Player MUST start at the
   ChapterTimeStart of the first chapter of the ordered chapter.  The
   enter commands of that chapter MUST be executed.  If that chapter
   contains Nested Chapters, the enter commands of the Nested Chapter
   with the same ChapterTimeStart MUST be executed.  If that chapter
   contains Nested Chapters, the enter commands of the Nested Chapter
   with the same ChapterTimeStart MUST be executed, and so on until
   there is no Nested Chapter with the same ChapterTimeStart.

   When switching from a chapter to another:

   *  the leave commands (ChapProcessTime=2) of the chapter MUST be
      executed, then the leave commands of its parent chapter, etc.
      until the common Parent Chapter or Edition element.  The leave
      command of that Parent Chapter or Edition element MUST NOT be
      executed.

   *  the enter commands (ChapProcessTime=1) of the Nested Chapter of
      the common Parent Chapter or Edition element, to reach the chapter
      we switch to, MUST be executed, then the enter commands of its
      Nested Chapter to reach the chapter we switch to MUST be executed,
      until that chapter is the chapter we switch to.  The enter
      commands of that chapter MUST be executed as well.

   When the last Chapter finished playing -- i.e. its ChapterTimeEnd has
   been reached -- the Matroska Player MUST execute its leaved commands,
   then the leave commands of it's Parent Chapter, until the parent of
   the chapter is the Edition.

7.1.  Matroska Script (0)

   This is the case when ChapProcessCodecID = 0.  This is a script
   language build for Matroska purposes.  The inspiration comes from
   ActionScript, javascript and other similar scripting languages.  The
   commands are stored as text commands, in UTF-8.  The syntax is C
   like, with commands spanned on many lines, each terminating with a
   ";".  You can also include comments at the end of lines with "//" or
   comment many lines using "/* */".  The scripts are stored in
   ChapProcessData.  For the moment ChapProcessPrivate is not used.

   The one and only command existing for the moment is GotoAndPlay(
   ChapterUID );. As the same suggests, it means that, when this command
   is encountered, the Matroska Player SHOULD jump to the Chapter
   specified by the UID and play it.







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7.2.  DVD menu (1)

   This is the case when ChapProcessCodecID = 1.  Each level of a
   chapter corresponds to a logical level in the DVD system that is
   stored in the first octet of the ChapProcessPrivate.  This DVD
   hierarchy is as follows:

    +====================+======+===========+==========+=============+
    | ChapProcessPrivate | DVD  | Hierarchy | Commands | Comment     |
    |                    | Name |           | Possible |             |
    +====================+======+===========+==========+=============+
    | 0x30               | SS   | DVD       | -        | First Play, |
    |                    |      | domain    |          | Video       |
    |                    |      |           |          | Manager,    |
    |                    |      |           |          | Video Title |
    +--------------------+------+-----------+----------+-------------+
    | 0x2A               | LU   | Language  | -        | Contains    |
    |                    |      | Unit      |          | only PGCs   |
    +--------------------+------+-----------+----------+-------------+
    | 0x28               | TT   | Title     | -        | Contains    |
    |                    |      |           |          | only PGCs   |
    +--------------------+------+-----------+----------+-------------+
    | 0x20               | PGC  | Program   | *        |             |
    |                    |      | Group     |          |             |
    |                    |      | Chain     |          |             |
    |                    |      | (PGC)     |          |             |
    +--------------------+------+-----------+----------+-------------+
    | 0x18               | PG   | Program 1 | -        |             |
    |                    |      | / Program |          |             |
    |                    |      | 2 /       |          |             |
    |                    |      | Program 3 |          |             |
    +--------------------+------+-----------+----------+-------------+
    | 0x10               | PTT  | Part Of   | -        | Equivalent  |
    |                    |      | Title 1 / |          | to the      |
    |                    |      | Part Of   |          | chapters on |
    |                    |      | Title 2   |          | the sleeve. |
    +--------------------+------+-----------+----------+-------------+
    | 0x08               | CN   | Cell 1 /  | -        |             |
    |                    |      | Cell 2 /  |          |             |
    |                    |      | Cell 3 /  |          |             |
    |                    |      | Cell 4 /  |          |             |
    |                    |      | Cell 5 /  |          |             |
    |                    |      | Cell 6    |          |             |
    +--------------------+------+-----------+----------+-------------+

                                 Table 1





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   You can also recover wether a Segment is a Video Manager (VMG), Video
   Title Set (VTS) or Video Title Set Menu (VTSM) from the
   ChapterTranslateID element found in the Segment Info.  This field
   uses 2 octets as follows:

   1.  Domain Type: 0 for VMG, the domain number for VTS and VTSM

   2.  Domain Value: 0 for VMG and VTSM, 1 for the VTS source.

   For instance, the menu part from VTS_01_0.VOB would be coded [1,0]
   and the content part from VTS_02_3.VOB would be [2,1].  The VMG is
   always [0,0]

   The following octets of ChapProcessPrivate are as follows:

   +=========+======+=================================================+
   | Octet 1 | DVD  | Following Octets                                |
   |         | Name |                                                 |
   +=========+======+=================================================+
   | 0x30    | SS   | Domain name code (1: 0x00= First play, 0xC0=    |
   |         |      | VMG, 0x40= VTSM, 0x80= VTS) + VTS(M) number (2) |
   +---------+------+-------------------------------------------------+
   | 0x2A    | LU   | Language code (2) + Language extension (1)      |
   +---------+------+-------------------------------------------------+
   | 0x28    | TT   | global Title number (2) + corresponding TTN of  |
   |         |      | the VTS (1)                                     |
   +---------+------+-------------------------------------------------+
   | 0x20    | PGC  | PGC number (2) + Playback Type (1) + Disabled   |
   |         |      | User Operations (4)                             |
   +---------+------+-------------------------------------------------+
   | 0x18    | PG   | Program number (2)                              |
   +---------+------+-------------------------------------------------+
   | 0x10    | PTT  | PTT-chapter number (1)                          |
   +---------+------+-------------------------------------------------+
   | 0x08    | CN   | Cell number [VOB ID(2)][Cell ID(1)][Angle       |
   |         |      | Num(1)]                                         |
   +---------+------+-------------------------------------------------+

                                 Table 2

   If the level specified in ChapProcessPrivate is a PGC (0x20), there
   is an octet called the Playback Type, specifying the kind of PGC
   defined:

   *  0x00: entry only/basic PGC

   *  0x82: Title+Entry Menu (only found in the Video Manager domain)




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   *  0x83: Root Menu (only found in the VTSM domain)

   *  0x84: Subpicture Menu (only found in the VTSM domain)

   *  0x85: Audio Menu (only found in the VTSM domain)

   *  0x86: Angle Menu (only found in the VTSM domain)

   *  0x87: Chapter Menu (only found in the VTSM domain)

   The next 4 following octets correspond to the User Operation flags in
   the standard PGC.  When a bit is set, the command SHOULD be disabled.

   ChapProcessData contains the pre/post/cell commands in binary format
   as there are stored on a DVD.  There is just an octet preceding these
   data to specify the number of commands in the element.  As follows:
   [# of commands(1)][command 1 (8)][command 2 (8)][command 3 (8)].

   More information on the DVD commands and format on DVD from the
   [DVD-Info] project.

8.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

9.  Informative References

   [DVD-Info] "DVD-Video Information",
              <http://dvd.sourceforge.net/dvdinfo/>.

Authors' Addresses

   Steve Lhomme
   Email: slhomme@matroska.org


   Moritz Bunkus
   Email: moritz@bunkus.org


   Dave Rice



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   Email: dave@dericed.com


















































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